1. Field of the Invention
The present invention relates to a rotary connector for connecting relatively rotatable members.
2. Description of the Related Art
Among various rotary connectors for connecting relatively rotatable members, a rotary connector for an automotive air bag is well known, for example. This type of a rotary connector has relatively rotatable fixed and rotatable cases and a flat cable loosely wound in spiral form and housed in the cases, and loosening and tightening of the flat cable permit the rotatable case to rotate relatively to the fixed case.
The flat cable includes a plurality of parallel conductors covered with an insulating material, and the inner and outer ends of the spirally wound cable are each bent and extended through the opening of the respective case to outside, or the conductors are connected to one end of a connection terminal arranged at the opening of the respective case. A lead wire connected to an external device or the like is connected to the other end of the connection terminal by means of welding or the like, and the connected portion is molded, using a synthetic resin, so that the flat cable may be protected from a tensile stress acting on the connected portion.
The conductors of the flat cable are, however, flat and thin and their strength against a bending force is not very high. Therefore, when the flat cable is bent, disconnection of the conductors sometimes occurs.
The connection of the lead wire to the connection terminal and the molding of the connected portion are preferably carried out after the flat cable is housed within the cases, for readiness of operation. If, in this case, the lead wire fails to be held in a predetermined position, however, the position for connection of the connection terminal and the lead wire is shifted due to a tensile stress acting on the lead wire. As a result, the connection terminal and the lead wire cannot be securely connected and the strength of the flat cable is reduced at the connected portion. Moreover, even after the connected portion is molded using a synthetic resin, its strength against a tensile stress acting on the lead wire cannot be sufficiently high for every occasion.